CN103864836A - Alkoxysilyl group-containing azo compound and rubber composition using the same - Google Patents

Abstract

The present invention provides an azo compound containing an alkoxysilyl group represented by the following formula (1), a method for simply obtaining the azo compound containing an alkoxysilyl group, and a A rubber composition having improved heat generation properties and the like is obtained using the azo compound. The azo compound containing an alkoxysilyl group is preferably obtained by reacting a compound represented by the following formula (2) with a compound represented by the following formula (3): wherein R ¹ and R ² represent a compound having 1-3 carbon atoms An alkyl group, R ³ and R ⁸ represent an alkylene group with 1-3 carbon atoms, R ⁴ , R ⁵ , R ⁶ and R ⁷ represent hydrogen or an alkyl group with 1-3 carbon atoms, n is 1 An integer of -3, and m is an integer of 1-5. HS-(CH ₂ ) _m -Si(OR ¹ ) _n (R ² ) _3-n (3).

Description

Azo compound containing alkoxysilyl group and rubber composition using the same

technical field

The present invention relates to a novel azo compound containing an alkoxysilyl group, which can be used as a radical generator (radical generator) reactive to silica and metal oxides, and relates to a method for preparing said azo compound The method, the rubber composition using the azo compound, and the pneumatic tire (pneumatic tire) using the rubber composition.

Background technique

When silica is used in a rubber composition, various sulfur-containing silane coupling agents are used in order to improve the dispersibility of silica. The properties of the rubber are affected by the silane coupling agent added. Therefore, for example, a silane coupling agent capable of improving less heat generation required, for example, in tires is required.

A polymer having a functional group introduced into a molecular terminal is useful because the functional group can be used for a crosslinking reaction of the polymer and can be used for stabilizing the dispersibility of fillers such as silica particles. In particular, for a polymer having an alkoxysilyl group at the terminal, it is expected that the polymer can form a crosslinking point by polycondensation and be used as a silane coupling agent that is hydrolyzed with an inorganic material such as Silica particles) react on the surface.

Regarding the introduction of terminal functional groups into polymers, for example, JP-A-8-104710 (1996) describes the reaction of alkoxysilanes having isocyanate groups and azo compounds having functional groups reactive with isocyanate groups to form macromolecules Azo radical initiators with which alkoxysilyl-terminated vinyl polymers are obtained.

Japanese Patent No. 2510345 discloses an azo compound containing an alkoxysilyl group, which can be used as a radical polymerization initiator to provide a new polymerization method, and records that the compound can be the same as a silane coupling agent way to use. As the preparation method of the compound, a method of reacting an azo compound containing an ester group or an amide group with a primary amine containing an alkoxysilyl group in the presence of a metal alkoxide catalyst is disclosed.

However, isocyanate groups and metal alkoxides used in the production methods of the above-mentioned conventional techniques have high reactivity to water, and thus there are problems that synthesis conditions are strictly limited in any production method and yields are low. Based on the above facts, azo compounds containing alkoxysilyl groups have not yet been practically used as silane coupling agents.

Contents of the invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel azo compound containing an alkoxysilyl group, which is useful as a radical generator. Another object of the present invention is to provide a method for producing alkoxysilyl group-containing azo compounds in high yield, which can react even in the presence of water. Another object of the present invention is to provide a rubber composition using the azo compound containing an alkoxysilyl group as a new silane coupling agent, which has various improved rubber properties (such as less fever).

In order to overcome the above problems, the azo compound containing alkoxysilyl group of the present invention is represented by the following formula (1):

Wherein R ¹ and R ² each independently represent an alkyl group with 1-3 carbon atoms, R ³ and R ⁸ each independently represent an alkylene group with 1-3 carbon atoms, R ⁴ , R ⁵ , R ⁶ and R ^each independently represent hydrogen or an alkyl group having 1-3 carbon atoms, n is an integer of 1-3, and m is an integer of 1-5.

The method of the present invention for preparing the azo compound containing an alkoxysilyl group comprises making a compound represented by the following formula (2):

wherein R ³ and R ⁸ each independently represent an alkylene group having 1-3 carbon atoms, and R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen or an alkyl group having 1-3 carbon atoms ;

react with a compound represented by the following formula (3):

HS-(CH ₂ ) _m -Si(OR ¹ ) _n (R ² ) _3-n (3)

Wherein R ¹ and R ² each independently represent an alkyl group with 1-3 carbon atoms, n is 1-3

Integer, and m is an integer of 1-5,

Thereby, an azo compound containing an alkoxysilyl group represented by formula (1) was prepared.

The above-mentioned production method can use a radical generating agent as a reaction catalyst.

The azo compound containing an alkoxysilyl group of the present invention contains an alkoxysilyl group reactive to silica or the like. Therefore, when the azo compound is used as, for example, a radical generator, a polymer having an alkoxysilyl group at one or both ends is obtained.

According to the production method of the present invention described above, mercaptoalkoxysilane is added to the terminal alkenyl group of the azo compound by a thiol-ene reaction. Therefore, the azo compound containing an alkoxysilyl group of the present invention can be obtained efficiently even in the presence of water.

The rubber composition of the present invention contains an azo compound represented by formula (1).

In the rubber composition of the present invention, the azo compound represented by formula (1) is preferably represented by the following formula (1'):

wherein the definitions of R ¹ , R ² , R ³ , R ⁸ , n and m are the same as in formula (1).

The pneumatic tire of the present invention is obtained by using the rubber composition of the present invention.

According to the rubber composition of the present invention, the exothermic properties of the rubber can be reduced by using the alkoxysilyl group-containing azo compound represented by formula (1) as the silane coupling agent. The azo compound containing an alkoxysilyl group generates carbon radicals by thermal decomposition and bonds to rubber molecules through a carbon-carbon bond. Therefore, it is considered that the formation of a strong bond contributes to the reduction of the exothermic properties of the rubber, ie, the improvement in less exothermic properties, compared with conventional polysulfide silane coupling agents.

Detailed ways

Embodiments for carrying out the present invention are described in detail below.

The alkoxysilyl group-containing azo compound of the present invention has a structure represented by formula (1). For simplicity, the compound of the present invention represented by formula (1) is sometimes referred to as "azo compound (1)" hereinafter.

In formula (1), R ¹ and R ² each independently represent an alkyl group having 1-3 carbon atoms, R ³ and R ⁸ each independently represent an alkylene group having 1-3 carbon atoms, R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen or an alkyl group having 1-3 carbon atoms, n is an integer of 1-3, and m is an integer of 1-5.

According to the intended use of the azo compound (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , n and m are preferably selected from the above ranges. For example, when using an azo compound (1) as a free radical generator to prepare a polymer that can be used as a silane coupling agent, R ¹ and R ² are preferably methyl or ethyl, and R ³ and R ⁸ preferably have 1 - an alkylene group of 3 carbon atoms, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are preferably hydrogen or an alkyl group having 1 to 3 carbon atoms. n is preferably 3, and m is preferably 2-4, particularly preferably 3.

"Each independently" described as a proviso of formula (1), R ¹ , R ² , n and m in the group bonded to one end of the azo group may be bonded to the other end of the azo group R ¹ , R ² , n and m in the group are the same or different. In addition, each of ^R3 and ^R8 may be the same or different, and ^R4 and ^R5 and ^R6 and ^R7 may each be the same or different. In other words, the azo compound (1) may be centered on the azo group and be bilaterally symmetrical or bilaterally asymmetric.

However, when the azo compound (1) is used as a free radical generator, if the azo compound (1) is asymmetric with the azo group as the center, two free radicals with different structures and reactivity are generated . Therefore, the reaction product obtained using the azo compound (1) is a mixture of two or more kinds, and the molecular weight distribution is generally broad. Therefore, for example, in order to obtain a polymer having a narrow molecular weight distribution, the azo compound (1) is preferably bilaterally symmetrical.

The azo compound (1) of the present invention combines the azo compound represented by the formula (2) (hereinafter referred to as " Compound (2)") obtained by thiol-ene reaction between terminal alkenyl groups. Thiol-ene reactions are addition reactions in which thiols and carbon-carbon double bonds add to each other 1:1. Specifically, sulfur-containing radicals are readily generated and added to carbon-carbon double bonds by UV radiation or radical initiators such as peroxides. A 1:1 adduct is formed when the resulting carbon radical abstracts the hydrogen from the thiol. Free radicals that have been deprived of hydrogen are transformed into sulfur-containing free radicals, therefore, the reaction proceeds in chain form.

The azo compound (1) of the present invention is formed by the thiol-ene addition reaction between the compound (2) and the compound (3) as described above. Therefore, R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ in compound (2) and R ¹ , R ² , n and m in compound (3) are selected to obtain the expected even Nitrogen compounds (1). Compound (2) and compound (3) may be used alone as one kind, or may be used as a mixture of two or more kinds, depending on the intended use of the azo compound (1).

The amounts of compound (2) and compound (3) used in the production method of the present invention are adjusted so that compound (3) is introduced at both ends of compound (2). Specifically, the proportion of thiol in compound (3) is preferably 1 mol or more, and more preferably 1 to 1.2 mol, per 1 mol of alkenyl group in compound (2).

In the thiol-ene reaction used in the production method of the present invention, a radical generator as a reaction catalyst is not always necessary. However, when a radical generator is used, the reaction can proceed more easily. The type and the like of the radical generating agent are not particularly limited. The 10-hour half-life temperature (T10) is preferably 5°C or more lower, more preferably 15°C or more lower, and particularly preferably 30-70°C lower than the 10-hour half-life temperature of compound (2) and the expected azo compound (1) .

Specific examples of suitable free radical generators include azo compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (T10: 30°C), 2,2 '-Azobis(2,4-dimethylvaleronitrile) (ADVN, T10:51℃), 2,2'-azobis(2-methylpropionate dimethyl)(T10:66℃) , 2,2'-azobis(2-methylbutyronitrile) (AMBN, T10:67℃), 1,1'-azobis(cyclohexane-1-carbonitrile)(T10:88℃) and 2,2'-Azobis(isobutyronitrile) (AIBN, T10:65°C). Among them, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile) are preferred because The temperature conditions of the thiol-ene addition reaction can be lowered.

The reaction conditions, reaction apparatus and the like for the reaction of the compound (2) and the compound (3) are appropriately selected according to the conditions and the like conventionally used for a thiol-ene reaction, and are not particularly limited. Usually, the reaction is preferably carried out at a temperature of 20-70°C for about 10 minutes to 3 hours.

As described above, the azo compound containing an alkoxysilyl group of the present invention is used as a radical generator to obtain a polymer having an alkoxysilyl group at the terminal, and can also be generated by in situ reaction with iodine As an initiator for iodine transfer polymerization. In addition, the azo compound can be used as a silane coupling agent for rubber and a modifier for various polymers. In addition, a graft polymer is prepared by subjecting the surface of a metal oxide or the like to a fixing (fixing) treatment, followed by polymerization. The term "immobilized" as used herein means that the azo compound can be chemically bonded to the surface of a solid substance through hydrolysis of an alkoxy group, etc., can be physically bonded (eg, hydrogen bond), or can be trapped in pores of a solid surface. The presence or absence of elements in the azo compound on the curing-treated surface after curing treatment and subsequent washing with an organic solvent or the like can be measured by using energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) or the like to fix it.

The rubber composition of the present invention is described below.

The rubber usable in the rubber composition of the present invention is not particularly limited, and examples thereof include various diene rubbers such as various natural rubbers (NR), various polyisoprene rubbers (IR), various styrene rubbers, - Butadiene rubber (SBR) and various polybutadiene rubbers (BR). These rubbers may be used in any one or in admixture of two or more. Styrene-butadiene rubber and various polybutadiene rubbers are preferably used. As these rubbers, modified diene rubbers into which amino groups, alkoxysilyl groups, hydroxyl groups, epoxy groups, carboxyl groups, cyano groups, halogen groups, etc. have been introduced may be used as necessary.

The rubber composition of the present invention may contain reinforcing fillers generally used in the field of rubber without particular limitation. This is based on the premise that the rubber composition contains silica to obtain the intended effect of the present invention. Examples of other reinforcing fillers include carbon black, talc, clay, aluminum hydroxide and titanium oxide. Among them, carbon black is preferably used. These reinforcing fillers other than silica may be used alone or in admixture of two or more thereof.

The added amount of the reinforcing filler is not particularly limited, and is appropriately adjusted depending on the intended use of the tire member and the like. In general, the addition amount of silica is preferably 10 to 120 parts by mass per 100 parts by mass of the rubber component. In addition to silica, carbon black is preferably added in an amount of 5 to 50 parts by mass per 100 parts by mass of the rubber component. The addition ratio of silica and carbon black is particularly preferably in the range from 1/20 to 1/0.1 as silica/carbon black ratio.

The alkoxysilyl group-containing azo compound of the present invention having a structure represented by formula (1) is used in the rubber composition of the present invention. The azo compound represented by formula (1) is particularly preferably a compound represented by the following formula (1'):

In formula (1′), R ¹ and R ² each represent an alkyl group having 1 to 3 carbon atoms, and each is preferably a methyl group or an ethyl group. R ³ and R ⁸ each represent an alkylene group having 1 to 3 carbon atoms, and each is preferably an alkylene group having 1 to 2 carbon atoms. n is an integer of 1-3, and is preferably 3. m is an integer of 1-5, and preferably an integer of 2-4, and particularly preferably 3.

According to the rubber composition of the present invention, when the azo compound represented by the formula (1) is used, the effects of greatly improving various properties of the rubber, such as reducing heat generation of the rubber, improving reinforcement, suppressing Mooney, etc., can be obtained. Viscosity increase and deterioration of anti-scorch properties are suppressed. The effect becomes particularly remarkable when an azo compound represented by formula (1') is used. It is considered that improvement in these properties becomes remarkable when the azo compound represented by formula (1) is obtained from a raw material having a high 10-hour half-life temperature. The 10-hour half-life temperature of the raw material is preferably 50°C or higher, and more preferably 80-120°C.

The content of the azo compound (1) in the rubber composition of the present invention is preferably 1 to 15% by mass, and more preferably 1 to 10% by mass, based on the mass of silica. When the content of the azo compound (1) is 1% by mass or more based on the mass of silica, the effect of improving rubber properties expected by the present invention is remarkably achieved. Even if the content exceeds 15% by mass, there is no problem. However, an amount of 15% by mass or less is favorable for the balance between cost and effect.

The rubber composition of the present invention may further contain a silane coupling agent other than the azo compound (1), as long as the object of the present invention is not impaired. The kind of the silane coupling agent is not particularly limited, and silane coupling agents generally used in rubber compositions for tires can be used. Examples of usable silane coupling agents include sulfurized silanes or mercaptosilanes. The amount of the silane coupling agent used other than the azo compound (1) is preferably 1-15% by mass of the total amount of the silane coupling agent and the azo compound (1), based on the amount of silica quality meter.

In addition to the above-mentioned reinforcing fillers and silane coupling agents, the rubber composition of the present invention may suitably contain various additives commonly used in rubber compositions for tires, such as zinc white, stearic acid, antiaging agents, waxes and vulcanizing agents. Examples of vulcanizing agents include sulfur and sulfur-containing compounds. Although not particularly limited, the vulcanizing agent is added in an amount of preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass per 100 parts by mass of the rubber component. The rubber composition is prepared by kneading according to a conventional method using a general kneader for rubber, such as a Banbury mixer or a kneader.

The rubber composition described above can be used as a tread rubber or a sidewall rubber of a tire. When the rubber composition is vulcanized and molded at a temperature of 140-180° C. according to a conventional method, a tire can be formed.

Examples of the present invention are described below, but the present invention is not limited to these Examples. Unless otherwise specified, the formula ratios shown below are all based on mass (parts by mass, % by mass, etc.).

Synthesis Example 1

Synthesis of 2,2'-azobis[2-methyl-N-(3-(3-(triethoxysilyl)propylthio)propyl)propionamide]

20 g of 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide] (VF-096, 10-hour half-life temperature: 96° C., manufactured by Wako Pure Chemical Industries, Ltd.), 34.5g of 3-mercaptopropyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.66g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70, 10-hour half-life temperature: 30°C, manufactured by Wako Pure Chemical Industries, Ltd.) and 55 g of toluene were placed in an eggplant flask. The flask was purged with nitrogen for 20 minutes while stirring with a magnetic stirrer, then capped tightly. The flask containing the reaction solution was placed in a water bath maintained at 35° C., and the reaction was performed with stirring for 2 hours. The obtained reaction product was concentrated by an evaporator, and then purified by column chromatography.

¹ H-NMR and ¹³ C-NMR analysis of the purified reaction product confirmed that the reaction product was 2,2'-azobis[2-methyl-N-(3-(3-(triethoxy silyl)propylthio)propyl)propionamide]. The analysis results of ¹ H-NMR and ¹³ C-NMR are shown below.

¹ H-NMR (400MHz, TMS standard=0.0ppm):1.34(s,12H,=NC(CH ₃ ) ₂ -),7.0(s,2H,-C(=O)NH-),3.46(q, 4H,NH- CH ₂ -CH ₂ -),1.85(m,4H,NH-CH ₂ -CH 2 _- ),2.54(q,8H,-CH 2 _-SC H ₂ -),1.69(m ,4H,-CH ₂ -S-CH ₂ -CH ₂ -),0.73(t,4H,-CH 2 _-Si- (O-CH ₂ -CH ₃ ) ₃ ),3.82(q,12H,-CH ₂ -Si-( OCH ₂ -CH ₃ ) ₃ ), 1.23 (t, 18H, -CH ₂ -Si-(O-CH ₂ -CH ₃ ) ₃ ).

¹³ C-NMR (400MHz, TMS standard=0.0ppm): 74.7(=N C (CH ₃ ) ₂ -), 23.1(=NC( CH ₃ ) ₂ -), 173.8(- C (=O)NH- ), 38.6(NH- CH ₂ -CH ₂ -), 29.5(NH-CH ₂ -CH ₂ -), 29.2(- CH ₂ -S-CH ₂ - ) , 35.2(-CH ₂ -S- CH ₂ -),23.2(-CH ₂ -S-CH ₂ -CH ₂ -),9.95( -CH ₂ -Si-(O-CH ₂ -CH ₃ ) ₃ ),58.4(-CH ₂ - Si-(O- CH ₂ -CH ₃ ) ₃ ), 18.3(-CH ₂ -Si-(O-CH ₂ -CH ₃ ) ₃ ).

Synthesis Example 2

Synthesis of 2,2'-azobis[2-methyl-N-(3-(3-(trimethoxysilyl)propylthio)propyl)propionamide]

20g of 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide] (VF-096, manufactured by WakoPure Chemical Industries, Ltd.), 33.5g of 3-mercaptopropyltrimethoxy Silane (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.66 g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70, manufactured by Wako Pure Chemical Industries , Ltd.) and 55 g of toluene were placed in an eggplant-shaped flask. The flask was purged with nitrogen for 20 minutes while stirring with a magnetic stirrer, then capped tightly. The flask containing the reaction solution was placed in a water bath maintained at 35° C., and the reaction was performed with stirring for 2 hours. The obtained reaction product was concentrated by an evaporator, and then purified by column chromatography.

The purified reaction product was analyzed by ¹ H-NMR and ¹³ C-NMR, and it was confirmed that the reaction product was 2,2'-azobis[2-methyl-N-(3-(3-(trimethoxymethyl silyl)propylthio)propyl)propionamide]. The analysis results of ¹ H-NMR and ¹³ C-NMR are shown below.

¹ H-NMR (400MHz, TMS standard=0.0ppm):1.34(s,12H,=NC(CH ₃ ) ₂ -),7.0(s,2H,-C(=O)NH-),3.46(q, 4H,NH- CH ₂ -CH ₂ -),1.85(m,4H,NH-CH ₂ -CH 2 _- ),2.54(q,8H,-CH 2 _-SC H ₂ -),1.69(m ,4H,-CH ₂ -S-CH ₂ -CH ₂ -),0.72(t,4H,-CH 2 -Si-(O-CH ₃ ) ₃ ) _, 3.55(s,18H,-CH ₂ - Si—( OCH ₃ ) ₃ )).

¹³ C-NMR (400MHz, TMS standard=0.0ppm): 74.7(=N C (CH ₃ ) ₂ -), 23.1(=NC( CH ₃ ) ₂ -), 173.8(- C (=O)NH- ), 38.6(NH- CH ₂ -CH ₂ -), 29.5(NH-CH ₂ -CH ₂ -), 29.2(- CH ₂ -S-CH ₂ - ) , 35.2(-CH ₂ -S- CH ₂ -),23.2(-CH ₂ -S-CH ₂ -CH ₂ -),9.94( -CH ₂ -Si-(O-CH ₃ ) ₃ ),50.2(-CH ₂ -Si-( O- CH ₃ ) ₃ ).

Azo compound as the use embodiment of methyl methacrylate polymerization initiator

50 g of methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.5 g of the azo compound obtained in Synthesis Example 1 above, and 50 g of toluene were placed in an eggplant-shaped flask, and the flask was magnetically stirred The vessel was purged with nitrogen for 15 minutes while stirring, then capped tightly. The reaction was stirred for 3 hours in an oil bath maintained at 95°C. The resulting reaction solution was purified by reprecipitation with ethanol to obtain a reaction product.

The obtained reaction product was analyzed by ¹ H-NMR and ¹³ C-NMR, and its molecular weight was measured by gel permeation chromatography. It was confirmed that a methyl methacrylate polymer (number average molecular weight: 100,000, weight average molecular weight: 250,000) was obtained. From this result, it can be seen that the azo compound containing an alkoxysilyl group in the examples of the present invention has the capability of initiating radical polymerization.

Preparation Example of Rubber Composition

According to the formulations shown in the following Tables 1 and 2 (unless otherwise specified, parts by mass), the components except sulfur and vulcanization accelerator were mixed, and then sulfur and vulcanization accelerator were added and mixed to prepare tires for use in tires. rubber composition. The details of each blend in Tables 1 and 2 are as follows:

SBR1: SBR1502, prepared by JSR Corporation

SBR2: SBR0122, prepared by JSR Corporation

Carbon black: SEAST3, manufactured by Tokai Carbon Co., Ltd.

Silica: Ultrasil VN3, manufactured by Evonik Industries

Silane coupling agent: Si75, manufactured by Evonik Industries

Azo compound A: 2,2'-Azobis[N-(2-propenyl)-2-methylpropionamide] represented by the following formula (manufactured by Wako Pure Chemical Industries, Ltd.):

Azo compound B: the azo compound containing alkoxysilyl group obtained by Synthesis Example 1

Oil: Extract#4S, prepared by Showa Shell Sekiyu K.K.

Zinc White: Zinc White#1, manufactured by Mitsui Mining & Smelting Co., Ltd.

Stearic acid: LUNAC S20, manufactured by Kao Corporation

Antiaging agent: NOCRAC6C, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

Wax: OZOACE0355, manufactured by Nippon Seiro Co., Ltd.

Sulfur: sulfur powder, manufactured by Tsurumi Chemical Industry Co., Ltd.

Vulcanization accelerator 1: SOXINOL CZ, manufactured by Sumitomo Chemical Co., Ltd.

Vulcanization accelerator 2: NOCCELER D, manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

The heat generation properties, 300% modulus, Mooney viscosity and scorch resistance of each of the rubber compositions obtained above were measured and evaluated by the following methods. The results obtained are shown in Tables 1 and 2.

Heat generation: The loss factor tan δ was measured according to JIS K6394 under the following conditions: temperature: 70° C., frequency: 10 Hz, static strain: 10%, dynamic strain: 2%, and the value of Comparative Example 1 was expressed as an index when the value was 100 (index). The results show that the smaller this index is, the smaller tan δ is, which means lower heat generation, that is, excellent heat generation.

300% tensile modulus: The tensile test (dumbbell #3 form) was performed according to JIS K6251, and when the value of Comparative Example 1 was 100, the modulus value of 300% elongation was expressed as an index. The results showed that the larger the value, the higher the modulus and excellent the strength (reinforcement).

Mooney viscosity: Mooney viscosity ML(1+4) at 100° C. was measured according to JIS K6300, and the value of Comparative Example 1 was expressed as an index when the value was 100. The results show that the smaller the index is, the lower the viscosity is and the processing performance is excellent.

Scorch resistance: According to JIS K6330-1, the t5 value was measured at 125°C after preheating for 1 minute using a Mooney scorch tester (L-shaped rotor), and the value of Comparative Example 1 was expressed as one when the value was 100 index. The results showed that the larger the index, the less scorch occurred, and the scorch resistance was excellent.

Table 1

The results shown in Table 1 show that, compared with Comparative Example 1, in Comparative Examples 2 and 3 to which the azo compound A was added, reinforcement decreased and heat generation increased. The reason for this phenomenon is considered to be that the azo compound A does not contain an alkoxysilyl group, and the silica dispersing effect is small. On the other hand, in Examples 1 and 2 in which azo compound B having a high 10-hour half-life temperature of the raw material azo compound was added, heat generation was reduced and reinforcement was increased. In addition to this, an increase in Mooney viscosity is suppressed and significant deterioration in scorch resistance is suppressed.

Table 2

The results shown in Table 2 above show that, similar to the results shown in Table 1, compared with Comparative Example 4, in Comparative Examples 5 and 6 using an azo compound not containing an alkoxysilyl group In , reinforcement decreases and heat increases. In Examples 3 and 4 to which the azo compound B was added, the heat generation was reduced and the reinforcement was increased. In addition to this, an increase in Mooney viscosity is suppressed and deterioration in scorch resistance is suppressed.

Claims (6)

1. An azo compound containing an alkoxysilyl group represented by the following formula (1): Wherein R ¹ and R ² each independently represent an alkyl group with 1-3 carbon atoms, R ³ and R ⁸ each independently represent an alkylene group with 1-3 carbon atoms, R ⁴ , R ⁵ , R ⁶ and R ^each independently represent hydrogen or an alkyl group having 1-3 carbon atoms, n is an integer of 1-3, and m is an integer of 1-5. 2. A method for preparing an azo compound containing an alkoxysilyl group, which comprises reacting a compound represented by the following formula (2) with a compound represented by the following formula (3), thereby preparing claim 1 Azo compounds containing alkoxysilyl groups; Described formula (2) is:

wherein R ³ and R ⁸ each independently represent an alkylene group having 1-3 carbon atoms, and R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen or an alkyl group having 1-3 carbon atoms ; Described formula (3) is: HS-(CH ₂ ) _m -Si(OR ¹ ) _n (R ² ) _3-n (3) wherein R ¹ and R ² each independently represent an alkyl group having 1-3 carbon atoms, n is an integer of 1-3, and m is an integer of 1-5. 3. The method for producing an alkoxysilyl group-containing azo compound according to claim 2, comprising using a radical generator as a reaction catalyst. 4. A rubber composition containing the alkoxysilyl group-containing azo compound represented by formula (1) according to claim 1. 5. The rubber composition according to claim 4, comprising a compound represented by the following formula (1') as the azo compound containing an alkoxysilyl group:

Wherein R ¹ and R ² each independently represent an alkyl group with 1-3 carbon atoms, R ³ and R ⁸ each independently represent an alkylene group with 1-3 carbon atoms, n is an integer of 1-3, And m is an integer of 1-5. 6. A pneumatic tire using the rubber composition according to claim 4 or 5.